Anna Gancarczyk

Hydrodynamics of pulsing flow in three-phase chemical reactors ☆

Abstract In the present study verification is carried out of mathematical criteria that define the boundary between two hydrodynamic regimes: the gas continuous flow (GCF) regime and the pulsing flow (PF) regime. Attention is focused on the criterion derived using the model of K. Grosser, R.G. Carbonell and S. Sundaresan, AIChE J., 34 (1988) 1850–1860, and the parametric sensitivity of this criterion is analysed. Next, based on the measured values of the gas pressure drop in a reactor the verification of some selected parameters is carried out by fitting the theoretical and experimental boundary lines separating the GCF and PF regimes. Experimental results are also presented concerning the determination of parameters characterising the pulsing flow through the bed, namely the frequency of pulsations and the pulse structure. These parameters were determined for the system nitrogen–water, and also for liquids differing from water in their physicochemical properties.

Short-Channel Structured Reactor as a Catalytic Afterburner

Short-channel structures of triangular and sinusoidal channel cross-sectional shape were examined experimentally to find their heat (or mass) transfer and flow friction (flow resistance) characteristics. A particular emphasis was placed on influence of the channels length (referred to its hydraulic diameter) on transport and hydrodynamic characteristics. The transport and friction properties were correlated in terms of dimensionless channel length with satisfactory accuracy. The dimensionless channel length was proved to be a key factor that determines the transport and friction coefficients. Comparison with ceramic monolith has shown possibility of using the structures in automotive catalytic converters.

Non-Noble Metal Oxide Catalysts for Methane Catalytic Combustion: Sonochemical Synthesis and Characterisation

The aim of this study was to obtain nanocrystalline mixed metal-oxide–ZrO2 catalysts via a sonochemically-induced preparation method. The effect of a stabiliser’s addition on the catalyst parameters was investigated by several characterisation methods including X-ray Diffraction (XRD), nitrogen adsorption, X-ray fluorescence (XRF), scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectrometer (EDS), transmission electron microscopy (TEM) and µRaman. The sonochemical preparation method allowed us to manufacture the catalysts with uniformly dispersed metal-oxide nanoparticles at the support surface. The catalytic activity was tested in a methane combustion reaction. The activity of the catalysts prepared by the sonochemical method was higher than that of the reference catalysts prepared by the incipient wetness method without ultrasonic irradiation. The cobalt and chromium mixed zirconia catalysts revealed their high activities, which are comparable with those presented in the literature.